In the power tool art, there are several power tools which are characterized by and/or which are oftentimes used in combination with flat, horizontal, work-supporting tables and wherein the tables are provided with straight, elongate, horizontally extending upwardly projecting work guiding and/or work stop parts which serve to orient work and to assist the operators of the tools to work across the tops of the tables and relative to the work performing elements or parts of the power tools. Those work guiding and/or work stop parts are commonly referred to as "fences".
The most familiar class of power tools with which fences of the character referred to above are commonly related are table saws. Table saws are characterized by rectangular tables with flat, horizontal, work-supporting top surfaces, vertical slot-like blade openings in the tables, electric motors mounted beneath the tables and flat, disc-shaped saw blades carried by the shafts of the motors and having upper portions projecting freely through the blade openings and upwardly from the top surfaces of the tables.
Table saws of the character referred to above are such that work can be engaged atop the tables and manually moved thereacross and relative to the blades to effect the making of desired cuts therein. In the course of using table saws, to assure the making of straight predetermined cuts in work and to prevent the work and saw blades from binding and causing serious adverse effects, the work must be carefully and accurately moved across the tables in straight lines, parallel with the radial planes of the saw blades.
To enable the work to be moved across the tables and relative to the blades of table saws in the manner set forth above, fences of the general character here concerned with and referred to above are utilized. The elongate fences are suitably mounted on the tops of the tables on lines spaced axially from and parallel with the radial planes of the saw blades and work to be cut is engaged and supported atop the tables, in advance of the saw blades and is moved into stopped engagement with the fences. Thereafter, the work is manually moved longitudinally of the fences and is advanced to and by the saw blades to effect the desired cuts therein.
The lines of cuts to be made in work varies infinitely. Accordingly, it is necessary that the lateral spacing of the fences relative to the radial planes of the saw blades must be varied and adjusted so that work is cut along desired lines. The lateral spacing or distance between the fences and the sawblades determines the "width" of the cuts to be made in the work and it is therefore the width of cuts which is determined by lateral movement and adjustment of the fences relative to the blades in table saws.
In the case of some table saws provided by the prior art, fences are not provided and the users of those saws must build their own fence structures. In such cases, the fence structures commonly consist of straight board, clamped and held in desired position atop the saw tables by C-clamps or the like. In other cases, table saws are provided with adjustable fence structures which include elongate work engaging fences which are substantially coextensive with the longitudinal extent of the tables and are parallel with the radial planes of the saw blades. Such adjustable fences are supported by cars or other suitable guide members or parts slidably carried by or engaged in longitudinally spaced transversely extending rails or grooves carried by or formed in the tables. Adjustable fence structures of the character referred to in the foregoing are such that lateral positioning of the fences relative to the saw blades can be accurately adjusted to infinitely vary the width of cut to be made in the work. In the case of such adjustable fence structures, manually operable locking means are commonly provided to releasably lock the cars (or equivalent means) in desired set position relative to the rails (or grooves) with which they are related. While many of the adjustable fence structures provided by the prior art are theoretically effective, the great majority of those structures are in fact such that they are subject to setting the fences in misalignment with their related saw blades and therefore such that they must be operated and set with great care. As a result of the foregoing, they are frequently extremely slow, time-consuming and troublesome to operate.
A major shortcoming which exists in adjustable table saw fence structures of the general character referred to above resides in the fact that they are built into their related tables in such a manner that the maximum width of cuts that can be made therewith is unduly limited. In order to overcome the foregoing limitation, the manufacturers of some table saws provide heavy and costly table saw extensions with which their adjustable fences can be related. While such saw table extensions increase the range of the width of cut that can be made, most extensions are of such limited size and extent that they seldom afford an adequately wide range of adjustment to meet the requirement and/or desires of the majority of table saw owners and operators.
Throughout the art in which table saws are used, there is a large and ever-increasing number of instances where the owners and operators of table saws construct large and expansive table saw tables to replace the original tables of their table saws or construct large and expansive saw table extensions engageable with and/or about the relatively small tables of inexpensive commercially available table saws provided by the prior art. Such large and expensive replacement saw tables or saw table extensions are commonly established of sheets of plywood or the like and are used by those who, in the normal course of using their table saws, frequently have to work with and cut full 4 ft. by 8 ft. sheets of plywood or the like and/or cut other large fabricated panel-like structures. In such instances, the fences provided with the table saws are useless and the operators of the saws must improvise and use jury-rigged type fence structures of questionable effectiveness.
While some manufacturers of table saws provided saw tables of sufficient size to conveniently handle full 4 ft. by 8 ft. plywood panels and the like, the price exacted for such tables is prohibitive for most individuals and small shops and are seldom cost-effective under the best of circumstances.
Another undesirable characteristic found to exit in the fence structures for table saws and other power tools, against which work is engaged and along which work is moved, resides in the tendency of the work to stick, catch or otherwise "hand up" on the fences and in doing so to create a multitude of problems and adverse effects too numerous to recite. While it is understood that certain special fence structures with work-engaging roller bearings or the like have been provided by the prior art to prevent the hanging up of work on the fences, to the best of may knowledge and belief, no such structures has been made which is sufficiently simple and economical to make to have attained any commercial success. Accordingly, the need for a fence structure which assures free movement of work relative thereto and which is simple and inexpensive has not been satisfied by the prior art.